In spite of the wide variety
of materials they handle, all well equipped scrap metal recyclers
have at least one thing in common – a good alligator
shear. Alligator shears play an important role for metal recyclers
by cutting things down to size – literally – enabling
shredders to handle oversized materials that would otherwise
be difficult or sometimes impossible to digest. They also
allow the recycler to “clean” or prepare scrap
for shredding by removing unwanted fittings or other parts
the shredder may not accept. This adds value to the scrap
and improves the quality of the finished frag.

This month, we’ll look
at stationary alligator-style shears and provide some basic
guidelines for choosing the right alligator shear for your
needs.

Feeding
the beast

Alligator shears take their
name from the style of jaw. The top blade is hinged on one
end and is driven by a hydraulic cylinder. Like the swamp
dwelling reptile, it exerts tremendous force on the downward
stroke, shearing off nearly anything a scrap metal recycler
may feed it. But, there are limitations for everything, as
we’ll discuss later.

The first consideration a
scrap metal recycler should look at is the range of materials
he plans to cut. This is known as the “appetite”
of the shear. The jaw size and cutting force determines the
appetite of the shear. Curt Spivey, vice president of sales
and marketing for Sweed Recycling Machinery, Inc., distributors
of Ramjet alligator-style shears points out, “Recyclers
should know exactly what they plan to process. Most manufacturers
publish an appetite guide to help recyclers size the correct
shear for their operation. Typical materials include such
scrap items as pipe, angle, cable, tubing, rounds, rebar and
some I-beam,” he said.

In addition to cutting some
items to a manageable length, a lot of times scrap yards must
remove certain fittings or clean things off the material they
process because they can’t be recycled for some reason.
Preparing materials like those for a shredder can bring as
much as $20-$30 more per ton for the recycler,” he added.

Don’t
stand too close

Alligator shears pack a lot
of cutting power, but the force exerted on the material being
cut varies widely, depending on the make, model and target
application. On the small end, an 8” alligator shear
has a cutting force of roughly 25 tons. This is adequate for
small diameter rounds, angle iron, rebar and some light gauge
sheet. Larger alligators produce as much as 200 tons or more
of shearing force – suitable for small I-beams, some
plate steel and other heavy scrap.

With that much force being
applied, safety is the primary consideration among manufacturers
of alligator shears. “Our products are equipped with
breaks, guards and blocks to be sure the piece stays secure
while it’s in the shear,” said Curt Spivey. According
to Sweed Recycling Equipment, a serrated knife-edge, most
commonly the bottom-shearing blade, is often used to keep
material from moving away from the pivot point while the top
jaw is closing under pressure.

Some models offer other safety
features such as dual switch controls – a system of
two switches placed a few feet apart that require the operator
to press both simultaneously to cycle the shear. Standards
for machine guards such as those fitted to alligator shears
are listed in OSHA regulation 29 CFR 1910.212.

In spite of the huge cutting
forces applied, there are some materials better left to the
torch or some other means for cleaning or reduction. “Alligator-style
shears are great for their intended use, but there are certain
things that shouldn’t be attempted,” said Curt
Spivey. “Hardened materials such as axles, rail or leaf
springs can damage the cutting knives,” he added.

Caring
for your alligator

Generally speaking, maintenance
on alligator shears is very low. Due to the wide variety of
materials processed and the amount of use each shear may get,
blades will wear at wildly differing rates. A recycler cleaning
larger volumes of scrap or has customers with more cut-to-length
requirements will need to inspect his blades frequently to
ensure maximum throughput and performance.

When they need attention,
most manufacturers recommend that blades, or cutting knives,
be replaced rather than sharpened. This is due primarily to
the somewhat limited capabilities among most metals recyclers
to properly recondition worn blades and restore them to the
manufacturers’ original equipment specifications. By
replacing blades when necessary, operators can be assured
of maintaining the highest levels of safety, performance and
productivity.

Bobby Alexander, president
of Ft. Worth, Texas-based Strip Technology, Inc., distributors
of the popular McIntyre shears said, “Keep it greased.
There’s several pivot points on an alligator shear that
require lubrication, and the best way to handle that chore
is on a regular basis. It’s a lot better to schedule
a maintenance routine, say once a month, and be sure it’s
done faithfully regardless of how much use a shear may get
in between. The habit of performing regular maintenance doesn’t
take much time and it’s a lot less costly than repairs,”
he said.

Generally speaking, the hydraulic
system on an alligator shear requires nearly no maintenance
at all. “All the manufacturers use good components to
begin with,” said Bobby Alexander. “And they’re
well engineered. The hydraulics feature in-line filters for
the fluid, pick-up screens in the reservoir and temperature
gauges to be sure things don’t overheat. Alligator shears
are a bit like 35mm cameras today,” he said. “It’s
just about impossible to buy a bad one.”